Most computers today use a "mouse" to control the location of a cursor on the screen. It is important to be able to quickly and accurately position the cursor, especially when working with programs having a graphical user interface. The mouse is a simple device which uses a roller ball. As the mouse is moved, the roller ball moves two perpendicular sensors. One sensor detects movement towards or away from the user. The other sensor detects movements to the left or right of the user. These movements can be referred to as measured on an x-y plane. Thus, even angular movements will produce both an x-component and a y-component. These values are then translated into movement of a cursor displayed on the monitor.
The mouse, while revolutionary in its day, has numerous mechanical parts which can break or malfunction. A common problem is the accumulation of lint, carried by the roller ball and lodged against the sensor. This prevents the sensor from properly recording the movement of the roller ball. Further, the ball can become irregular with time, making it more difficult to roll. Another problem occurs when the mouse is placed upon a smooth surface. Even if the surface of the roller ball is textured, it can slide rather than roll. Again the result is unpredictable movement of the cursor on the screen.
A final problem exists regarding a handicapped user's ease of use. If the user has no hands or has been crippled, a tactile device such as a mouse is difficult to manipulate. A need exists for a method and apparatus to control a cursor's position without the use of a tactile mechanical device. Such a device in a more generic sense could be used in any hand's free interaction with a computer. For example, a severely handicapped user should be able to manipulate the device with the movement of a straw-like extension held in his mouth.
Such a computer interface need not be solely restricted to the manipulation of a personal computer. Many industries have used automated machinery to improve the efficiency of their production. The machinery is controlled by a program. Safety hazards are presented when workers work in proximity to automated machinery. It would be beneficial to have a means to detect the location of a worker and alter the movement of the automated machinery to avoid that location.
Finally, a need exists for an input device which seamlessly integrates with modern three-dimensional graphic displays. For example, "virtual reality" goggles and autostereoscopic projection devices produce three-dimensional images. A new input device is needed which allows a user to interact with the image without invasive tactile attachments.